code: def test_pr(dummy_classifier, mock_run):
      _ = mock_run(settings={"mode": "offline"})
      *_, y_test, _, y_probas = dummy_classifier
      custom_chart_no_title = pr_curve(y_test, y_probas)
      assert (
          custom_chart_no_title.string_fields["title"]
          == "Precision v. Recall"
      )
      first_row = custom_chart_no_title.table.data[0]
      assert first_row == [0, 1.0, 1.0], first_row
      custom_chart_with_title = pr_curve(
          y_test, y_probas, title="New title"
      )
      assert (
          custom_chart_with_title.string_fields["title"] == "New title"
      )
  
file_path: wandb/tests/pytest_tests/unit_tests/test_plot.py
imports: import pytest
  from sklearn.naive_bayes import MultinomialNB
  from wandb.plot import confusion_matrix, line_series, pr_curve, roc_curve
label_desc: Use image node_id 3 for calling a global function with example usage: test_pr(dummy_classifier, mock_run) without return types